On macOS, add tabbing APIs

This should let the users control macOS tabbing and allow to create
windows in tab.

Co-authored-by: Amr Bashir <amr.bashir2015@gmail.com>

examples/window_tabbing.rs

@@ -0,0 +1,105 @@
+#![allow(clippy::single_match)]
+
+#[cfg(target_os = "macos")]
+use std::{collections::HashMap, num::NonZeroUsize};
+
+#[cfg(target_os = "macos")]
+use simple_logger::SimpleLogger;
+#[cfg(target_os = "macos")]
+use winit::{
+    event::{ElementState, Event, KeyEvent, WindowEvent},
+    event_loop::EventLoop,
+    keyboard::Key,
+    platform::macos::{WindowBuilderExtMacOS, WindowExtMacOS},
+    window::{Window, WindowBuilder},
+};
+
+#[cfg(target_os = "macos")]
+#[path = "util/fill.rs"]
+mod fill;
+
+#[cfg(target_os = "macos")]
+fn main() {
+    SimpleLogger::new().init().unwrap();
+    let event_loop = EventLoop::new();
+
+    let mut windows = HashMap::new();
+    let window = Window::new(&event_loop).unwrap();
+    println!("Opened a new window: {:?}", window.id());
+    windows.insert(window.id(), window);
+
+    println!("Press N to open a new window.");
+
+    event_loop.run(move |event, event_loop, control_flow| {
+        control_flow.set_wait();
+
+        match event {
+            Event::WindowEvent { event, window_id } => {
+                match event {
+                    WindowEvent::CloseRequested => {
+                        println!("Window {window_id:?} has received the signal to close");
+
+                        // This drops the window, causing it to close.
+                        windows.remove(&window_id);
+
+                        if windows.is_empty() {
+                            control_flow.set_exit();
+                        }
+                    }
+                    WindowEvent::Resized(_) => {
+                        if let Some(window) = windows.get(&window_id) {
+                            window.request_redraw();
+                        }
+                    }
+                    WindowEvent::KeyboardInput {
+                        event:
+                            KeyEvent {
+                                state: ElementState::Pressed,
+                                logical_key,
+                                ..
+                            },
+                        is_synthetic: false,
+                        ..
+                    } => match logical_key.as_ref() {
+                        Key::Character("t") => {
+                            let tabbing_id = windows.get(&window_id).unwrap().tabbing_identifier();
+                            let window = WindowBuilder::new()
+                                .with_tabbing_identifier(&tabbing_id)
+                                .build(event_loop)
+                                .unwrap();
+                            println!("Added a new tab: {:?}", window.id());
+                            windows.insert(window.id(), window);
+                        }
+                        Key::Character("w") => {
+                            let _ = windows.remove(&window_id);
+                        }
+                        Key::ArrowRight => {
+                            windows.get(&window_id).unwrap().select_next_tab();
+                        }
+                        Key::ArrowLeft => {
+                            windows.get(&window_id).unwrap().select_previous_tab();
+                        }
+                        Key::Character(ch) => {
+                            if let Ok(index) = ch.parse::<NonZeroUsize>() {
+                                windows.get(&window_id).unwrap().select_tab_at_index(index);
+                            }
+                        }
+                        _ => (),
+                    },
+                    _ => (),
+                }
+            }
+            Event::RedrawRequested(window_id) => {
+                if let Some(window) = windows.get(&window_id) {
+                    fill::fill_window(window);
+                }
+            }
+            _ => (),
+        }
+    })
+}
+
+#[cfg(not(target_os = "macos"))]
+fn main() {
+    println!("This example is only supported on MacOS");
+}